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To prevent acute allergic reaction and allow the body to develop its own immunity to midge bites vitamin B1 (thiamine) can be tried. This vitamin has an anti-histamine type action. Biting midge expert, Dr. Eric Reye, suggests an adult dose of 200mg twice a day with meals, preferably starting 2 weeks before exposure to midge. As immunity is developed this dose can be reduced.

это из статьи про предупреждение реакции на укусы мокрецов